AVAggregateAssetDownloadTask不支持currentRequest属性，但可以通过实现AVAssetDownloadDelegate的方法来获取下载请求。例如：

let downloadTask = AVAggregateAssetDownloadTask(asset: asset, mediaSelections: mediaSelections, options: options)

downloadTask.delegate = self
downloadTask.resume()

...

// Implement AVAssetDownloadDelegate methods

extension ViewController: AVAssetDownloadDelegate {

    func urlSession(_ session: URLSession, assetDownloadTask: AVAssetDownloadTask, didFinishDownloadingTo location: URL) {

        if let originalRequest = assetDownloadTask.value(forKey: "originalURLRequest") as? URLRequest {
            print("Download request: \(originalRequest)")
        }

        // Handle downloaded asset here
    }
}

在AVAssetDownloadDelegate中的didFinishDownloadingTo方法中，通过获取originalURLRequest属性来获取下载请求。